Film frame substrate fixture

ABSTRACT

The present invention provides a fixture for mounting a substrate to mounting tape on a film frame so as to retain the substrate to the film frame for dicing. A plurality of grooves for receiving a cutting saw extend longitudinally and transversely across the fixture to define die regions. The fixture also includes a plurality of apertures that align with the substrate and with dies to be cut from the substrate. The aligned apertures supply vacuum to the substrate to retain the substrate and cut dies in the fixture. When the dicing is completed, the vacuum is turned off and the individual dies can be readily removed from the fixture.

This application is a divisional of application Ser. No. 09/293,151,filed on Apr. 16, 1999, now U.S. Pat. No. 6,321,739 which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to material handling machinesfor dicing semiconductor substrates. More particularly, the inventionrelates to film frames for holding substrates for dicing and, still moreparticularly, to fixtures coupled to the film frame for receiving andretaining the substrate in position on the film frame.

2. Description of the Related Art

Conventional substrate dicing machines include a film frame coupled to achuck by vacuum. The film frame includes a frame and mounting tapestretched across the frame. Typically, the mounting tape is a polymerfilm having an adhesive surface for holding a substrate to be diced.

In conventional operation, a substrate is mounted on the mounting tapeand the film frame is mounted on the chuck. Vacuum is applied to thebottom of the mounting tape. The vacuum stabilizes the mounting tape inthe vertical direction. When the substrate has been diced, the filmframe and substrate must be processed to remove the individual dies fromthe mounting tape. Unfortunately, dedicated equipment is required toremove the tape from the film frame. Moreover, the dedicated equipmentis expensive and takes up valuable floor space. In addition, the taperemoving process adds manufacturing steps, and the mounting tape isconsumed during the dicing process, adding to the cost of producingproducts which incorporate the diced dies.

SUMMARY OF THE INVENTION

The present invention overcomes the above-cited disadvantages byproviding a fixture that is mounted to the film frame by mounting tape.The fixture includes a recess configured to receive a substrate fordicing. A plurality of grooves for receiving a cutting saw extendlongitudinally and transversely across the fixture to define dieregions. As the cutting saw moves over the substrate and along thegrooves, the substrate is diced into individual dies. The film frame,fixture and tape are reusable with other substrates.

The fixture may also include a plurality of apertures that align withone or more apertures formed in the mounting tape. The aligned aperturessupply vacuum to the substrate from a vacuum source which retains thesubstrate in the fixture and which also retains the dies in place in thefixture after dicing. When the dicing is completed, the vacuum is turnedoff and the individual dies can be readily removed from the fixture.

The invention advantageously reduces the number of manufacturing stepsinvolved in the production of the dies. Moreover, since the cutting sawmoves along the grooves, the fixture is not destroyed in the dicingprocess and can be reused, and since the fixture allows the saw to dicethe substrate without destroying the mounting tape, the mounting tape isnot consumed in the process, thereby further reducing material costs.

These and other features and advantages of the invention will becomemore readily apparent from the following detailed description ofpreferred embodiments of the present invention which is provided inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a dicing machine coupled to a vacuum source anda controller.

FIG. 2 is a plan view of a film frame.

FIG. 3 is a side view of a substrate to be diced.

FIG. 4 is a top plan view of the substrate of FIG. 3.

FIG. 5 is a bottom plan view of the substrate of FIG. 3

FIG. 6 is a top plan view of a fixture for receiving the substrate ofFIG. 3 in a contact down orientation.

FIG. 7 is a bottom plan view of the fixture of FIG. 6.

FIG. 8 is a side view of the fixture of FIG. 6.

FIG. 9 is an end view of the fixture of FIG. 6.

FIG. 10 is a section view taken along line 10—10 of FIG. 6.

FIG. 11 is a top plan view of a fixture for receiving the substrate ofFIG. 3 in a contact up orientation.

FIG. 12 is a bottom plan view of the fixture of FIG. 11.

FIG. 13 is a side view of the fixture of FIG. 11.

FIG. 14 is an end view of the fixture of FIG. 11.

FIG. 15 is a section view taken along line 15—15 of FIG. 11.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A conventional film frame 10 for use in dicing a substrate isillustrated in FIG. 2. The frame 10 includes a generally annular plate12 having a pair of flats 14 on opposite sides of the plate 12 and apair of positioning notches 16 for receiving guide pins (not shown). Inoperation, a film having an adhesive surface for supporting a substrateis stretched across the frame 10. The frame 10 is mounted on the dicingmachine 15 and mechanical clamps retain the frame 10 in position.

Although the subsequent description shows a particular type ofsubstrate, e.g., an encapsulated substrate that includes a plurality ofchip packages having ball grid array connectors, the substrate shown ismerely exemplary. The invention can be used with a wide variety ofsubstrates, including semiconductor wafers, or portions thereof.

A substrate 20 to be diced is illustrated in FIGS. 3-5. The illustratedsubstrate 20 is a forty unit overmolded panel and includes a panel 22divided into four overmolded segments 24. Each segment 24 will produceten individual encapsulated packages 26 when diced. Each of the packageshas a plurality of contacts in the form of solder balls 28 formed as aball grid array (BGA) or fine pitch ball grid array (FBGA) 30 on thebottom of the panel 22, i.e., beneath each package 26. The panel 22further includes apertures 32 disposed between adjacent segments 24 andapertures 34 disposed along the longitudinal edges of the panel 22. Aplurality of cutting saw alignment marks 36 extend longitudinally andtransversely across the panel 22. The substrate 20 has three squarecorners 21 a and a beveled corner 21 b for orientation of the substrate20 in a fixture 40 described below.

FIGS. 6-10 illustrate a first embodiment of a fixture 40 for receivingthe substrate 20 in a “contacts down” configuration. The fixture 40includes a plate 42 having a two-stage central recessed area 44 (FIG.10), a plurality of longitudinal grooves 46 (FIGS. 6 and 9), and aplurality of transverse grooves 48 (FIGS. 6 and 10). The recessed area44 is sized and configured to receive the substrate 20 and includes ashallow panel-receiving region 44 a and a deeper contact-receivingregion 44 b. The grooves 46, 48 cooperate to define a plurality of dieregions 50 that are disposed to align with the packages 26 on thesubstrate 20. The grooves 46, 48 are sized to receive the blade of acutting saw 17 and extend below the level of the contact-receivingregion 44 b, so that the cutting saw 17 can completely through a panel22 disposed in the recessed area 44 without contacting any part offixture 40. A controller 21 (FIG. 1) controls the positioning of thecutting saw 17 in the grooves 46, 48 and the movement of the saw 17 tocut the substrate 20.

Each die region 50 includes a plurality of apertures 52 formed as anaperture array 54. The aperture array 54 matches the BGA 30 beneath eachpackage 26 so that each ball 28 in the BGA 30 fits into one of theapertures 52 of the aperture array 54. An additional plurality ofapertures 56 are formed in each die region 50 for supplying vacuum froma vacuum source 19 to retain each package 26 in the fixture 40 duringand after dicing.

The grooves 46,48 further define a plurality of non-die regions 60disposed along the periphery of the panel 22 and between the segments24. The non-die regions 60 include apertures 64 for supplying vacuum toretain the non-die regions of the substrate 20 in the fixture during andafter dicing.

The recessed area 44 a includes three circular corners 68 for receivingsquare corners 21 a on the substrate 20. The fourth corner 70 is roundedfor receiving a shaped corner 21 b on the substrate 20. The corners 68,70 cooperate to ensure that the substrate 20 is properly oriented in thefixture 40.

FIGS. 11-15 illustrate a second embodiment of the fixture 140 for use indicing the substrate 20. The fixture 140 includes a plate 142 having aone-stage central recessed area 144, a plurality of longitudinal grooves146, and a plurality of transverse grooves 148. The recessed area 144 issized and configured to receive the substrate 20 in a “contact up”configuration, wherein the encapsulant is disposed in the recessed area144. The grooves 146, 148 cooperate to define a plurality of die regions150 that are disposed to align with the packages 26 on the substrate.The grooves 146, 148 are sized to receive a cutting saw 17 and extendbelow the level of the recessed area 144 so that the cutting saw cutscompletely through a panel 22 disposed in the recessed area 144 withoutcontacting the fixture 140.

Each die region 150 includes a pair of apertures 153 for supplyingvacuum to retain each package 26 in the fixture during and after dicing.The grooves 146, 148 further define a plurality of non-die regions 160disposed along the periphery of the panel 22 and between the segments24. The non-die regions 160 include apertures 164 and 165 for supplyingvacuum to retain the non-die regions of the substrate 20 in fixture 140during and after dicing.

The recessed area 144 a includes three circular corners 168 forreceiving square corners 21 a on the substrate 20. The fourth corner 170is rounded for receiving a shaped corner 21 b on the substrate. Thecorners 168, 170 cooperate to ensure that the substrate 20 is properlyoriented in the fixture 40.

The use of the FIGS. 4-15 fixtures will now be described. One of thefixtures (FIGS. 6-10) is used for a contacts shown dicing, while theother fixture (FIGS. 11-15) is used for contact up dicing.

In use, mounting tape is stretched across the film frame 10 and thefixture 40 or 140 is mounted on the mounting tape. The tape is cut outbeneath fixture 40 or 140 to allow apertures 56, 64, 153, 164, and 165to receive a vacuum from the source 19 (FIG. 1) through the cut-outposition of the tape (FIGS. 6-10). The film frame 10 is mounted on achuck and a substrate 20 is positioned in the recess 44 or 144. Vacuumis then applied to the substrate 20 through the cutout in the tape andthrough the apertures in fixture 40 or 140 to retain the substrate 20 onthe fixture 40 or 140. The cutting saw is then moved through the grooves46, 48 or 146, 148 to dice the substrate 20. After the substrate hasbeen diced, the vacuum is turned off and the film frame 10 is removedfrom the chuck and the individual dies easily removed from the fixture40 or 140 for further processing. The film frame is returned to thechuck, another substrate 20 mounted on the fixture 40 or 140 and vacuumreapplied to retain a new substrate 20 for dicing. It will beappreciated that the substrate can be mounted on the fixture before thefixture is mounted on the film. Moreover, the fixture can be mounted onthe mounting tape before the film frame is mounted on the chuck. Inother words, the precise sequence of steps is not essential.

The present invention provides a fixture for mounting a substrate to afilm frame so as to retain the substrate for dicing without destroyingthe mounting tape during the dicing process. The fixture also reducesthe number of manufacturing steps involved and eliminates the need fordedicated and expensive equipment. In particular, the invention has beendescribed with respect to use with encapsulated substrates employingball grid array contact packages which are to be diced from thesubstrate. However, as noted, any substrate can be diced using thefixture of the invention. For example, the invention can be used withdifferently shaped substrates or to dice semiconductor wafers ofdifferent sizes or shapes. Therefore, the scope of the present inventionis not to be considered as limited by the specifics of the particularfixtures described above, but is only limited by the scope of theappended claims.

What is claimed is:
 1. A substrate dicing machine comprising: a cuttingsaw; a film frame positioned relative to the cutting saw; a film mountedto the film frame, said film having an adhesive surface; and a fixtureadhered to the film, the fixture being configured to receive anddirectly retain a substrate, without the use of an adhesive, for dicingby the cutting saw.
 2. The machine of claim 1 further including a vacuumsource, wherein the fixture includes a recessed area for receiving thesubstrate and a plurality of apertures formed in the recessed area, thefixture being coupled to the vacuum source for applying vacuum to thesubstrate to retain the substrate in the fixture during dicing.
 3. Themachine of claim 1 wherein the fixture includes a plurality oflongitudinal grooves and a plurality of transverse grooves, each groovebeing configured to receive the cutting saw for movement along thegroove, each groove having a depth relative to the recessed areasufficient to allow the cutting saw to cut completely through thesubstrate as the saw moves along the groove without contacting thefixture.
 4. The machine of claim 3 wherein the longitudinal andtransverse grooves cooperate to define a plurality of die regions andeach die region includes at least one aperture for receiving vacuum toretain the substrate in the fixture.
 5. A substrate dicing machinecomprising: a cutting saw; a film frame mechanically clamped into aposition relative to the cutting saw; a film mounted to the film frame,said film having an adhesive surface; and a fixture adhered to the film,the fixture being configured to receive and directly retain a substrate,without the use of an adhesive, for dicing by the cutting saw.
 6. Themachine of claim 5, further including a vacuum source, wherein thefixture is coupled to the vacuum source for applying vacuum directly tothe substrate to retain the substrate in the fixture during dicing. 7.The machine of claim 6, wherein said film has a plurality of openingssaid vacuum being applied to the substrate through said openings.
 8. Themachine of claim 7, wherein the fixture includes a recessed area forreceiving the substrate and a plurality of apertures formed in therecessed area.
 9. A substrate dicing machine comprising: a cutting saw;a film frame positioned relative to the cutting saw; a film mounted tothe film frame, said film having an adhesive surface; and a fixtureadhered to the film, the fixture including a recessed area for receivingand directly retaining a substrate without the use of an adhesive,wherein the recessed area includes at least one predetermined shapedarea.
 10. The machine of claim 9, wherein said predetermined shaped areais configured to receive a respective shaped portion formed on asubstrate to be received in said recessed area.
 11. The machine of claim9, wherein the recessed area includes first and second saidpredetermined shaped areas.
 12. The machine of claim 11, wherein saidfirst predetermined shaped area comprises a shape which is differentthan the shape of said second predetermined shaped area.
 13. The machineof claim 12, wherein said recessed area includes three said firstpredetermined shaped areas.